Chemical compound with formula NaCl
This article is about the chemical. For its familiar form, common table salt, see
Salt
. For the medical solutions, see
Saline (medicine)
. For the mineral, see
Halite
.
Sodium chloride
Sodium chloride crystals in a form of
halite
|
Crystal structure with sodium in purple and chloride in green
[1]
|
Names
|
IUPAC name
Sodium chloride
|
Other names
- common salt, regular salt
- halite, rock salt
- table salt, sea salt
- saline
|
Identifiers
|
|
|
|
|
|
3534976
|
ChEBI
|
|
ChEMBL
|
|
ChemSpider
|
|
ECHA InfoCard
|
100.028.726
|
EC Number
|
|
|
13673
|
KEGG
|
|
MeSH
|
Sodium+chloride
|
|
|
RTECS number
|
|
UNII
|
|
|
|
InChI=1S/ClH.Na/h1H;/q;+1/p-1
Y
Key: FAPWRFPIFSIZLT-UHFFFAOYSA-M
Y
InChI=1/ClH.Na/h1H;/q;+1/p-1
Key: FAPWRFPIFSIZLT-REWHXWOFAE
|
|
Properties
|
|
NaCl
|
Molar mass
|
58.443 g/mol
[2]
|
Appearance
|
Colorless cubic crystals
[2]
|
Odor
|
Odorless
|
Density
|
2.17 g/cm
3
[2]
|
Melting point
|
800.7 °C (1,473.3 °F; 1,073.8 K)
[2]
|
Boiling point
|
1,465 °C (2,669 °F; 1,738 K)
[2]
|
|
360 g/L (25°C)
[2]
|
Solubility
in
ammonia
|
21.5 g/L
|
Solubility
in
methanol
|
14.9 g/L
|
|
?30.2·10
?6
cm
3
/mol
[3]
|
|
1.5441 (at 589 nm)
[4]
|
Structure
[5]
|
|
Face-centered cubic
(
see text
),
cF8
|
|
Fm
3
m (No. 225)
|
|
a
= 564.02 pm
|
|
4
|
|
octahedral at Na
+
octahedral at Cl
?
|
Thermochemistry
[6]
|
|
50.5 J/(K·mol)
|
|
72.10 J/(K·mol)
|
|
?411.120 kJ/mol
|
Pharmacology
|
|
A12CA01
(
WHO
)
B05CB01
(
WHO
),
B05XA03
(
WHO
),
S01XA03
(
WHO
)
|
Hazards
|
NFPA 704
(fire diamond)
|
|
Lethal dose
or concentration (LD, LC):
|
|
3 g/kg (oral, rats)
[7]
|
Related compounds
|
|
Sodium fluoride
Sodium bromide
Sodium iodide
Sodium astatide
|
|
Lithium chloride
Potassium chloride
Rubidium chloride
Caesium chloride
Francium chloride
|
Supplementary data page
|
Sodium chloride (data page)
|
Except where otherwise noted, data are given for materials in their
standard state
(at 25 °C [77 °F], 100 kPa).
|
Chemical compound
Sodium chloride
,
[8]
commonly known as
edible salt
, is an
ionic compound
with the
chemical formula
NaCl
, representing a 1:1 ratio of
sodium
and
chlorine
ions. It is transparent or translucent, brittle,
hygroscopic
, and occurs as the mineral
halite
. In its edible form, it is commonly used as a
condiment
and
food preservative
. Large quantities of sodium chloride are used in many industrial processes, and it is a major source of sodium and
chlorine
compounds used as
feedstocks
for further
chemical syntheses
. Another major application of sodium chloride is
deicing
of roadways in sub-freezing weather.
Uses
[
edit
]
In addition to the familiar domestic uses of salt, more dominant applications of the approximately 250 million tonnes per year production (2008 data) include chemicals and de-icing.
[9]
Chemical functions
[
edit
]
Salt is used, directly or indirectly, in the production of many chemicals, which consume most of the world's production.
[10]
Chlor-alkali industry
[
edit
]
It is the starting point for the
chloralkali process
, the industrial process to produce
chlorine
and
sodium hydroxide
, according to the
chemical equation
This electrolysis is conducted in either a mercury cell, a diaphragm cell, or a membrane cell. Each of those uses a different method to separate the chlorine from the sodium hydroxide. Other technologies are under development due to the high energy consumption of the electrolysis, whereby small improvements in the efficiency can have large economic paybacks. Some applications of chlorine include
PVC
thermoplastics
production, disinfectants, and solvents.
Sodium hydroxide is extensively used in many different industries enabling production of paper, soap, and aluminium etc.
Soda-ash industry
[
edit
]
Sodium chloride is used in the
Solvay process
to produce
sodium carbonate
and
calcium chloride
. Sodium carbonate, in turn, is used to produce
glass
,
sodium bicarbonate
, and
dyes
, as well as a myriad of other chemicals. In the
Mannheim process
, sodium chloride is used for the production of
sodium sulfate
and
hydrochloric acid
.
Miscellaneous industrial uses
[
edit
]
Sodium chloride is heavily used, so even relatively minor applications can consume massive quantities. In
oil
and
gas
exploration, salt is an important component of drilling fluids in well drilling. It is used to
flocculate
and increase the
density
of the drilling fluid to overcome high downwell gas pressures. Whenever a drill hits a salt formation, salt is added to the drilling fluid to saturate the solution in order to minimize the dissolution within the salt stratum.
[9]
Salt is also used to increase the curing of concrete in cemented casings.
[10]
In textiles and dyeing, salt is used as a brine rinse to separate organic contaminants, to promote "salting out" of dyestuff precipitates, and to blend with concentrated dyes to increase yield in dyebaths and make the colors look sharper. One of its main roles is to provide the positive ion charge to promote the absorption of negatively charged ions of dyes.
[10]
For use in the
pulp and paper industry
, it is used to manufacture
sodium chlorate
, which is then reacted with
sulfuric acid
and a reducing agent such as
methanol
to manufacture
chlorine dioxide
, a
bleaching
chemical that is widely used to
bleach wood pulp
.
In tanning and leather treatment, salt is added to animal
hides
to inhibit microbial activity on the underside of the hides and to attract moisture back into the hides.
[10]
In rubber manufacture, salt is used to make
buna
,
neoprene
, and white rubber types. Salt brine and sulfuric acid are used to coagulate an emulsified
latex
made from chlorinated
butadiene
.
[10]
[9]
Salt also is added to secure the soil and to provide firmness to the foundation on which highways are built. The salt acts to minimize the effects of shifting caused in the subsurface by changes in humidity and traffic load.
[10]
Water softening
[
edit
]
Hard water
contains calcium and magnesium ions that interfere with action of
soap
and contribute to the buildup of a scale or film of alkaline mineral deposits in household and industrial equipment and pipes. Commercial and residential water-softening units use
ion-exchange resins
to remove ions that cause the hardness. These resins are generated and regenerated using sodium chloride.
[10]
[9]
Road salt
[
edit
]
The second major application of salt is for
deicing
and anti-icing of roads, both in
grit bins
and spread by
winter service vehicles
. In anticipation of snowfall, roads are optimally "anti-iced" with brine (concentrated
solution
of salt in water), which prevents bonding between the snow-ice and the road surface. This procedure obviates the heavy use of salt after the snowfall. For de-icing, mixtures of brine and salt are used, sometimes with additional agents such as
calcium chloride
and/or
magnesium chloride
. The use of salt or brine becomes ineffective below ?10 °C (14 °F).
Salt for de-icing in the United Kingdom predominantly comes from a single mine in
Winsford
in
Cheshire
. Prior to distribution it is mixed with <100 ppm of
sodium ferrocyanide
as an
anticaking agent
, which enables rock salt to flow freely out of the gritting vehicles despite being stockpiled prior to use. In recent years this additive has also been used in table salt. Other additives had been used in road salt to reduce the total costs. For example, in the US, a byproduct carbohydrate solution from sugar-beet processing was mixed with rock salt and adhered to road surfaces about 40% better than loose rock salt alone. Because it stayed on the road longer, the treatment did not have to be repeated several times, saving time and money.
[10]
In the technical terms of physical chemistry, the minimum freezing point of a water-salt mixture is ?21.12 °C (?6.02 °F) for 23.31 wt% of salt. Freezing near this concentration is however so slow that the
eutectic point
of ?22.4 °C (?8.3 °F) can be reached with about 25 wt% of salt.
[11]
Environmental effects
[
edit
]
Road salt ends up in fresh-water bodies and could harm aquatic plants and animals by disrupting their
osmoregulation
ability.
[12]
The omnipresence of salt in coastal areas poses a problem in any
coating
application, because trapped salts cause great problems in adhesion. Naval authorities and ship builders monitor the salt concentrations on surfaces during construction. Maximal salt concentrations on surfaces are dependent on the authority and application. The
IMO
regulation is mostly used and sets salt levels to a maximum of 50 mg/m
2
soluble salts measured as sodium chloride. These measurements are done by means of a
Bresle test
. Salinization (increasing salinity, aka
freshwater salinization
syndrome
) and subsequent increased metal leaching is an ongoing problem throughout North America and European fresh waterways.
[13]
In highway de-icing, salt has been associated with
corrosion
of bridge decks, motor vehicles, reinforcement bar and wire, and unprotected steel structures used in road construction.
Surface runoff
, vehicle spraying, and windblown salt also affect soil, roadside vegetation, and local surface water and groundwater supplies. Although evidence of environmental loading of salt has been found during peak usage, the spring rains and thaws usually dilute the concentrations of sodium in the area where salt was applied.
[10]
A 2009 study found that approximately 70% of the road salt being applied in the
Minneapolis-St Paul
metro area is retained in the local watershed.
[14]
Substitution
[
edit
]
Some agencies are substituting
beer
,
molasses
, and
beet
juice instead of road salt.
[15]
Airlines utilize more
glycol
and
sugar
rather than salt-based solutions for
deicing
.
[16]
Food industry and agriculture
[
edit
]
Salt is added to food, either by the food producer or by the consumer, as a flavor enhancer, preservative, binder,
fermentation
-control additive, texture-control agent, and color developer. The salt consumption in the food industry is subdivided, in descending order of consumption, into other food processing, meat packers,
canning
, baking, dairy, and grain mill products. Salt is added to promote color development in bacon, ham and other processed meat products. As a preservative, salt inhibits the growth of bacteria. Salt acts as a binder in
sausages
to form a binding gel made up of meat, fat, and moisture. Salt also acts as a flavor enhancer and as a
tenderizer
.
[10]
It is used as a cheap and safe
desiccant
because of its
hygroscopic
properties, making
salting
an effective method of
food preservation
historically; the salt draws water out of bacteria through
osmotic pressure
, keeping it from reproducing, a major source of food spoilage. Even though more effective desiccants are available, few are safe for humans to ingest. Many
microorganisms
cannot live in a salty environment: water is drawn out of their
cells
by
osmosis
. For this reason salt is used to
preserve
some foods, such as bacon, fish, or cabbage.
In many dairy industries, salt is added to cheese as a color-, fermentation-, and texture-control agent. The dairy subsector includes companies that manufacture creamery butter, condensed and evaporated milk, frozen desserts, ice cream, natural and processed cheese, and specialty dairy products. In canning, salt is primarily added as a flavor enhancer and
preservative
. It also is used as a carrier for other ingredients, dehydrating agent, enzyme inhibitor and tenderizer. In baking, salt is added to control the rate of fermentation in bread dough. It also is used to strengthen the
gluten
(the elastic protein-water complex in certain doughs) and as a flavor enhancer, such as a topping on baked goods. The food-processing category also contains grain mill products. These products consist of milling flour and rice and manufacturing cereal breakfast food and blended or prepared flour. Salt is also used a seasoning agent, e.g. in potato chips,
pretzels
, and cat and dog food.
[10]
Sodium chloride is used in veterinary medicine as
emesis
-causing agent. It is given as warm saturated solution. Emesis can also be caused by
pharyngeal
placement of small amount of plain salt or salt crystals.
Medicine
[
edit
]
Sodium chloride is used together with water as one of the primary solutions for
intravenous therapy
.
Nasal spray
often contains a
saline
solution.
Sodium chloride is also available as an oral tablet, and is taken to treat low sodium levels.
[17]
Firefighting
[
edit
]
Sodium chloride is the principal extinguishing agent in dry-powder
fire extinguishers
that are used on combustible metal fires, for metals such as magnesium, zirconium, titanium, and lithium (Class D extinguishers). The salt forms an oxygen-excluding crust that smothers the fire.
[18]
Cleanser
[
edit
]
Since at least
medieval
times, people have used salt as a cleansing agent rubbed on household surfaces. It is also used in many brands of
shampoo
, toothpaste, and popularly to de-ice driveways and patches of ice.
Infrared optics
[
edit
]
Sodium chloride crystals have a
transmittance
of at least 90% (through 1 mm) for
infrared
light having wavelengths in the range 0.2? 18
μm
.
[19]
They were used in optical components such as windows and lenses, where few non-absorbing alternatives existed in that spectral range. While inexpensive, NaCl crystals are soft and
hygroscopic
? when exposed to the water in ambient air, they gradually cover with "frost". This limits application of NaCl to dry environments, vacuum-sealed areas, or short-term uses such as prototyping. Materials that are mechanically stronger and less sensitive to moisture, such as
zinc selenide
and
chalcogenide glasses
, more widely used than NaCl.
Chemistry
[
edit
]
Solid sodium chloride
[
edit
]
In solid sodium chloride, each ion is surrounded by six ions of the opposite charge as expected on electrostatic grounds. The surrounding ions are located at the vertices of a regular
octahedron
. In the language of
close-packing
, the larger
chloride
ions
(167 pm in size
[20]
) are arranged in a cubic array whereas the smaller
sodium
ions (116 pm
[20]
) fill all the cubic gaps (octahedral voids) between them. This same basic structure is found in many other
compounds
and is commonly known as the
NaCl structure
or rock salt crystal structure. It can be represented as a
face-centered cubic
(fcc) lattice with a two-atom basis or as two interpenetrating face centered cubic lattices. The first atom is located at each lattice point, and the second atom is located halfway between lattice points along the fcc unit cell edge.
Solid sodium chloride has a melting point of 801 °C and liquid sodium chloride boils at 1465 °C. Atomic-resolution real-time video imaging allows visualization of the initial stage of crystal nucleation of sodium chloride.
[21]
The
Thermal conductivity
of sodium chloride as a function of temperature has a maximum of 2.03 W/(cm K) at 8 K (?265.15 °C; ?445.27 °F) and decreases to 0.069 at 314 K (41 °C; 106 °F). It also decreases with
doping
.
[22]
From cold (sub-freezing) solutions, salt crystallises with
water of hydration
as
hydrohalite
(the dihydrate NaCl·2
H
2
O
).
[24]
In 2023, it was discovered that under pressure, sodium chloride can form the hydrates NaCl·8.5H
2
O and NaCl·13H
2
O.
[25]
Aqueous solutions
[
edit
]
The attraction between the Na
+
and Cl
?
ions in the solid is so strong that only highly
polar solvents
like water dissolve NaCl well.
When dissolved in water, the sodium chloride framework disintegrates as the Na
+
and Cl
?
ions become surrounded by polar water molecules. These solutions consist of
metal aquo complex
with the formula [Na(H
2
O)
8
]
+
, with the Na?O distance of 250
pm
. The chloride ions are also strongly solvated, each being surrounded by an average of six molecules of water.
[26]
Solutions of sodium chloride have very different properties from pure water. The
eutectic point
is ?21.12 °C (?6.02 °F) for 23.31%
mass fraction
of salt, and the boiling point of saturated salt solution is near 108.7 °C (227.7 °F).
[11]
pH of sodium chloride solutions
[
edit
]
The pH of a sodium chloride solution remains ?7 due to the extremely weak basicity of the Cl
?
ion, which is the conjugate base of the strong acid HCl. In other words, NaCl has no effect on system pH
[27]
in diluted solutions where the effects of ionic strength and activity coefficients are negligible.
Stoichiometric and structure variants
[
edit
]
Common salt has a 1:1 molar ratio of sodium and chlorine. In 2013, compounds of sodium and chloride of different
stoichiometries
have been discovered; five new compounds were predicted (e.g., Na
3
Cl, Na
2
Cl, Na
3
Cl
2
, NaCl
3
, and NaCl
7
). The existence of some of them has been experimentally confirmed at high pressures and other conditions: cubic and orthorhombic NaCl
3
, two-dimensional metallic tetragonal Na
3
Cl and exotic hexagonal NaCl.
[29]
This indicates that compounds violating chemical intuition are possible, in simple systems under non-ambient conditions.
[30]
Occurrence
[
edit
]
Salt is found in the
Earth's crust
as the mineral
halite
(rock salt), and a tiny amount exists as suspended
sea salt
particles in the atmosphere.
[
citation needed
]
These particles are the dominant
cloud condensation nuclei
far out at sea, which allow the formation of
clouds
in otherwise
non-polluted
air
.
[31]
Production
[
edit
]
Salt is currently
mass-produced
by
evaporation
of
seawater
or
brine
from
brine wells
and
salt lakes
.
Mining
of rock salt is also a major source. China is the world's main supplier of salt.
[10]
In 2017, world production was estimated at 280 million
tonnes
, the top five producers (in million tonnes) being China (68.0), United States (43.0), India (26.0), Germany (13.0), and Canada (13.0).
[32]
Salt is also a byproduct of
potassium
mining.
See also
[
edit
]
References
[
edit
]
- ^
"Sodium Chloride (NaCl) Crystal"
. PhysicsOpenLab
. Retrieved
23 August
2021
.
- ^
a
b
c
d
e
f
Haynes, 4.89
- ^
Haynes, 4.135
- ^
Haynes, 10.241
- ^
Haynes, 4.148
- ^
Haynes, 5.8
- ^
Tucker, R. K.; Haegele, M. A. (1971). "Comparative acute oral toxicity of pesticides to six species of birds".
Toxicology and Applied Pharmacology
.
20
(1): 57?65.
doi
:
10.1016/0041-008x(71)90088-3
.
ISSN
0041-008X
.
PMID
5110827
.
- ^
Wells, John C. (2008),
Longman Pronunciation Dictionary
(3rd ed.), Longman, pp. 143 and 755,
ISBN
9781405881180
- ^
a
b
c
d
Westphal, Gisbert
et al.
(2002) "Sodium Chloride" in Ullmann's Encyclopedia of Industrial Chemistry, Wiley-VCH, Weinheim
doi
:
10.1002/14356007.a24_317.pub4
.
- ^
a
b
c
d
e
f
g
h
i
j
k
l
Kostick, Dennis S. (October 2010).
"Salt"
(PDF)
.
U.S. Geological Survey, 2008 Minerals Yearbook
.
- ^
a
b
Elvers, B.
et al.
(ed.) (1991)
Ullmann's Encyclopedia of Industrial Chemistry
, 5th ed. Vol. A24, Wiley, p. 319,
ISBN
978-3-527-20124-2
.
- ^
Rastogi, Nina Shen (16 February 2010).
"Salting the Earth"
.
Slate
.
ISSN
1091-2339
. Retrieved
11 March
2023
.
- ^
"Saltier waterways are creating dangerous 'chemical cocktails'
"
.
phys.org
.
- ^
"Most Road Salt Is Making It into Lakes And Rivers"
.
www.sciencedaily.com
. University of Minnesota. 20 February 2009
. Retrieved
27 September
2015
.
- ^
Casey, Michael.
"Turning to beet juice and beer to address road salt danger"
.
phys.org
.
- ^
"EASA Cautions on Organic Salt Deicing Fluid"
.
MRO Network
. 9 December 2016.
- ^
"Sodium Chloride for oral solution"
.
Cleveland Clinic
. Retrieved
9 March
2024
.
- ^
Bagot, Keith; Subbotin, Nicholas; Kalberer, Jennifer (November 2006).
"Evaluation of a New Liquid Fire-Extinguishing Agent for Combustible Metal Fires"
(PDF)
.
Federal Aviation Administration
.
U.S. Department of Transportation
. Retrieved
1 May
2024
.
- ^
Waynant, Ronald W.; Ediger, Marwood N. (2000). "Chapter 11: Optical Materials: Visible and Infrared".
Electro-optics Handbook
. New York: McGraw-Hill Professional Publishing. p. 11.20.
ISBN
0-07-068716-1
.
- ^
a
b
R. D. Shannon (1976). "Revised effective ionic radii and systematic studies of interatomic distances in halides and chalcogenides".
Acta Crystallogr A
.
32
(5): 751?767.
Bibcode
:
1976AcCrA..32..751S
.
doi
:
10.1107/S0567739476001551
.
- ^
Nakamuro, Takayuki; Sakakibara, Masaya; Nada, Hiroki; Harano, Koji; Nakamura, Eiichi (2021).
"Capturing the Moment of Emergence of Crystal Nucleus from Disorder"
.
Journal of the American Chemical Society
.
143
(4): 1763?1767.
doi
:
10.1021/jacs.0c12100
.
PMID
33475359
.
- ^
Sirdeshmukh, Dinker B.; Sirdeshmukh, Lalitha & Subhadra, K. G. (2001).
Alkali halides: a handbook of physical properties
. Springer. pp. 65, 68.
ISBN
978-3-540-42180-1
.
- ^
Klewe, B; Pedersen (1974). "The crystal structure of sodium chloride dihydrate".
Acta Crystallogr
.
B30
(10): 2363?2371.
Bibcode
:
1974AcCrB..30.2363K
.
doi
:
10.1107/S0567740874007138
.
- ^
Water-NaCl phase diagram. Lide, CRC Handbook of Chemistry and Physics, 86 ed (2005-2006), CRC pages 8-71, 8-116
- ^
University of Washington.
"Newly discovered form of salty ice could exist on surface of extraterrestrial moons"
. Phys.org.
- ^
Lincoln, S. F.; Richens, D. T. and Sykes, A. G. (2003) "Metal Aqua Ions" Comprehensive Coordination Chemistry II Volume 1, pp. 515?555.
doi
:
10.1016/B0-08-043748-6/01055-0
.
- ^
"Acidic, Basic, and Neutral Salts"
.
Flinn Scientific Chem Fax
. 2016
. Retrieved
18 September
2018
.
Neutralization of a strong acid and a strong base gives a neutral salt.
- ^
Burgess, J (1978).
Metal Ions in Solution
. New York: Ellis Horwood.
ISBN
978-0-85312-027-8
.
- ^
Tikhomirova, K. A.; Tantardini, C.; Sukhanova, E. V.; Popov, Z. I.; Evlashin, S. A.; Tarkhov, M. A.; Zhdanov, V. L. (2020). "Exotic Two-Dimensional Structure: The first case of Hexagonal NaCl".
The Journal of Physical Chemistry Letters
.
11
(10): 3821?3827.
doi
:
10.1021/acs.jpclett.0c00874
.
PMID
32330050
.
S2CID
216130640
.
- ^
Zhang, W.; Oganov, A. R.; Goncharov, A. F.; Zhu, Q.; Boulfelfel, S. E.; Lyakhov, A. O.; Stavrou, E.; Somayazulu, M.; Prakapenka, V. B.; Konopkova, Z. (2013). "Unexpected Stable Stoichiometries of Sodium Chlorides".
Science
.
342
(6165): 1502?1505.
arXiv
:
1310.7674
.
Bibcode
:
2013Sci...342.1502Z
.
doi
:
10.1126/science.1244989
.
PMID
24357316
.
S2CID
15298372
.
- ^
Mason, B. J. (2006). "The role of sea-salt particles as cloud condensation nuclei over the remote oceans".
Quarterly Journal of the Royal Meteorological Society
.
127
(576): 2023?32.
Bibcode
:
2001QJRMS.127.2023M
.
doi
:
10.1002/qj.49712757609
.
S2CID
121846285
.
- ^
Bolen, Wallace P. (January 2018).
"Salt"
(PDF)
.
U.S. Geological Survey, 2018 Mineral Commodity Summaries
.
Cited sources
[
edit
]
External links
[
edit
]
Wikimedia Commons has media related to
NaCl
.
Wikibooks
Cookbook
has a recipe/module on
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Inorganic
| Halides
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Chalcogenides
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Pnictogenides
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Oxyhalides
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Oxychalcogenides
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Oxypnictogenides
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Others
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Organic
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Salts and covalent derivatives of the
chloride
ion
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